Paint is a widely used means for preserving, protecting, and decorating any of numerous articles and items encountered daily. Typically, the paint is provided with a tint or color to accentuate, highlight, or blend the painted article with respect to its surrounds. Since literally thousands of tints or shades of paint may be produced, stocking shelves of most retail establishments preclude the premixing or coloring of the paint before it is shelved. Retail efficiency dictates that only a limited number of preblended colors be stocked, and that the remainder of the colors or tints be produced on site. To this end, it has previously been known to employ paint tinting or coloring machines of a mechanical type, employing manually actuated displacement pumps for selecting and injecting various colorants into a can of paint base for ultimate mixing. Computer paint tinting systems have also been known. The same have typically employed motor gear positive displacement pumps for dispensing selected quantities of colorants.
The previously known tinting machines have required extensive maintenance to clean, purge, and repair the machines so that some degree of integrity in the dispensing operation could be maintained. Additionally, previously known systems have been limited in resolution, with the capability of dispensing 0.01 oz as the smallest volume that might be dispensed. Such limitations on the amount of colorant that may be dispensed limits the minimum volume of paint that may be colored or mixed and further limits the resolution of color shades which might be obtained. Because of these limitations, the prior art often requires mixing of a full gallon of a particular shade or color even though only a quart may be necessary for undertaking the desired painting project. The result has been the need to dispose of the remaining three quarts of the mixed paint, a waste of money and a threat to the environment.
Previously known computerized systems have also been of limited resolution and flexibility, generally constrained to the formulating of previously determined recipes. Even those systems employing spectrophotometers to determine the color of a known item have typically been employed simply to select the established recipe most closely replicating that color.
The previously known displacement pumps or displacement pistons have also been given to wear from the abrasive nature of the colorant employed. Such wear threatens the system integrity, resolution, and repeatability and, ultimately, requires repair. Additionally, such previously known systems have typically been given to operator errors and calibration problems, since the dispensing of the colorant has simply been achieved by the filling of a cavity of variable volume.
The prior art paint tinting systems have also required mechanical mixers to keep the pigment in the colorant in suspension so that the colorant is of uniform density and character when dispensed.
It has further been known from the prior art that the smallest volume of colorant that might be dispensed is the size of a "drop" of that colorant, the same varying in size as a function of the colorant of interest. For certain tints or colors, a "drop" may constitute a substantial volume of colorant, the presence or absence of which in the resulting mix may noticeably affect the resulting color. Additionally, if a "drop" of colorant is allowed to remain suspended from the dispensing tube of the paint tinting machine, it may either inadvertently drop into the next can of paint placed under the machine, or simply harden in the dispensing tube, requiring time consuming cleaning and purging.